<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>

<body>
  <script>
    class Person {
      constructor(age, name) {
        this.age = age,
          this.name = name
      }
    }

    class XiaoMing extends Person {
      constructor(age, name) {
        super(age, name)
        this.gender = 'man'
      }
    }

    let p = new Person(18, 'wangkang')
    let x = new XiaoMing(25, 'wangkang')
    console.log(p)
    console.log(x)  
  </script>
</body>

</html>